$42$ is what percent of $100$ ?
Having a percent of something means that you get that percent out of every $100$ We can set up a proportion to find out what percent of $100$ we need to take to get $42$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{\text{part}}}{{\text{whole}}}$ Which things do we know, and what are we trying to find? We are trying to find the ${\text{percent}}$ . Is $100$ the ${\text{part}}$ or the ${\text{whole}}$ The $100$ is the ${\text{whole}}$ . This means the ${\text{part}}$ is $42$ $ \dfrac{{\text{percent}}}{100} = \dfrac{{42}}{{100}}$ If we divide the denominator of the fraction on the right by $1$ , it will be the same denominator of the fraction on the left. To keep things equal, let's also divide the numerator on the right by $1$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{42 \div 1}}{{100 \div 1}}$ $ \dfrac{{\text{percent}}}{100 } = \dfrac{{42}}{{100}}$ $ {\text{percent}} = {42}$ So $42$ is $42\%$ of $100$.